Several systems are known in the art for learning electronics by setting-up circuits; below can be found a classification of the most important ones following the excellent topological analysis made by Mr. Reinhard Niehoff in his website called Erinacom.
2.1. Classification of the Known Systems
2.1.1. Systems in which the Connections Among Elements is Done through Cables (Verdrahtungssysteme in German).
In these systems the base panel solely accomplishes the function of supporting the modular pieces; the panel does not have any electrical function. Among these we can distinguish:
2.1.1.1. Open systems (Offenes Verdrahtungssystem): in these, the modular elements to be used are chosen from a “warehouse” and are fixed to the panel. The selected elements are later on connected through cables, wires, etc. In many of these systems the electronic components are fixed to small non-conductive cassette decks; this protects the components and makes them easier to use. Devices can be fixed to these cassette decks as a bridge between the leads of the electronic components and the cables that make the connections among decks. Normally, devices that allow connection of more than one cable with a component lead are used to achieve electric contact. Typical systems are those that use clamps (Klemmen in German), or plugs and sockets. When substitution of one element with another is desired, the element is simply disconnected and replaced with the new element, and once again the electric connections are to be done. An advantage of this system is that the elements can be easily laid out either very far or very near from the others. This can be interesting, for example, if one wants to minimize electromagnetic emissions or adapt it to a very large space, respectively. Notable examples of open systems are, among others, the Radiomann system of the German enterprise Kosmos. Initially, the contacts were done with clamps of screws and, later on, with clamps of flexible metal sheets. This system was available from 1934 until approximately 1972, when the Kosmotronik system was introduced and, later on, Electric X, which are characterized by a different set-up method: a network of straps. Another system of this type is that of another German enterprise, Busch.2.1.1.2. Closed systems (Geschlossenes Verdrahtungssystem): in these systems all the electronic components are fixed in an irremovable way to a panel. Next to each component are also fixed the means to connect the component to the interconnection cables. These connection means are permanently joined together to the leads of the electronic components. To achieve a circuit, one simply makes the necessary connections. The advantage of this system is that the components never get lost; the main disadvantage is that once the assembly has been done, it is very difficult to distinguish the electrical plan and understand its operation. Oftentimes the cables form a genuine puzzle and one easily commits errors. Another disadvantage is that many of the connections have to be made with long cables since the components are distant from each other. Still another negative factor is that the components cannot be increased, the assemblies have to be necessarily set up with the parts that come with it from its manufacturing.2.1.2. Contact network systems (Knotenraster): in these systems the contacts among the different elements are not done through cable but rather they are done in specific places of the contact network that the panel has. That is, in these systems the panel does not only undertake a support function but also an electrical function. The contact network of the panel can take different forms and the contacts done through varied means (clamps, springs, clips, screws, etc.). The contact network systems are undoubtedly the most elegant, above all, because the assemblies are very visual and look like the circuit diagram. Another advantage is that it is very easy to substitute an element with that of another of the same family but of different value. There are different types of contact networks and below are mentioned the more important ones:2.1.2.1. Network of contact points (Einfache Knotenraster): This system is also known as grid of contacts. This is the simplest and most basic network. It consists of establishing a network of contacts in the panel, in each one of which it is possible to connect one or various leads of the electronic components. In this way, when two or more leads coincide in one point, the leads become connected. In the network of contact points, the connections occur when two or more leads come in direct contact with each other. What the springs, clamps, etc. do is press together the leads. In order to achieve a network system of contact points, some preliminary conditions should be present. In the first place, the contact points should be made with parts that accept leads, cables, wires, etc. that accede the point from any direction. This is the purpose served, for example, of the springs placed in a vertical position with respect to the panel or the clamps (Klemmen in German). In the second place, the electronic components should be adequate; among others, the electronic components of the SMD type (Surface Mounted Device) are of no use because they do not have any leads. Of no use either are components with short leads that do not manage to reach two adjacent points in the contact network, or components so big that they exceed the distance between two adjacent points in the contact grid. One of the most representative examples of the system of contact points is the Philips system which dominated the sector between the years 1963 and 1983 approximately. What is most distinctive in the Philips system are the springs with which the contacts are done. These springs consist of two parts: a fastener that is introduced through the rear side of the perforated panel, and the spring itself, which surrounds the fastener in the front side of the panel. The spring pushes down the cables introduced by the fastener creating in that manner electrical contact. Although in the Philips system springs are placed only on determined points of the grid, this detail does not alter its operating principle, in such a way that this method can be perfectly classified under this present section.2.1.2.2. Network of crosses (Kreuzknotenraster): in the network of crosses there is no direct contact between leads. Each lead of a component touches a single contact, and each contact touches only a lead, or none. Electrical connection between leads is achieved because the contacts are joined together inside or over the panel. Usually, the contacts are grouped into groups of four. These groups, depending on the system, form a cross, a square, lines, etc. In these networks, the leads of the components are usually not found in a parallel plane to the panel but rather the leads are usually found perpendicular to the panel. The circuits done with these networks are simple and easy to manage. However, it is a system that requires a lot of space, above all for the components which have more than two contacts. The cross system, given the large space it needs, is used above all in the professional sector, such as in schools and universities, and more concretely, to put up assemblies in front of a class, as a demonstration. The usual contacts used are the typical banana connector of 4 mm.2.1.2.3. Network of squares (Quadratknotenraster): this system is similar to the prior one. Their only difference lies in the groups of contacts, whereas before they were a cross, now they are squares. This is achieved simply by rotating the groups 45°. This difference has at least one major consequence: now each contact can accept both horizontal as well as vertical units. This allows the parts to be placed in a more versatile way and occupy lesser space. On the other hand, the assemblies lose some of the clarity that they had in the cross network. A very common example of this type of system is the Spanish system Scatron. The details of this can be found in the patent document number ES 445733 A1.2.1.2.4. Network of strips of contacts (Streifenraster): here the contacts are placed in a linear manner, either horizontal or vertically. The number of contacts in each strip varies from one system to another, but the usual number is that of four or five. As examples of this system we can cite that of “Electronic XN” and “Electronic X”, of the German enterprise Kosmos.2.1.2.5. Breadboards: the network of strips of contacts reminds us very much of the breadboards that are found in electronic shops. These boards are usually formed by rows of five contacts and not of four. These rows are very close to each other, the usual distance is that of 2.54 mm, 0.1 inches, which is the standard distance of the pins of integrated circuits. In this way, the integrated circuits can be directly plugged to the board without using any type of adapter. It is important to note that these boards are rather a base to place the components, with an almost one-dimensional layout, unlike the networks that we have been referring to, which have a two-dimensional character. In order to achieve a two-dimensional network with these assembly boards, it is necessary to use more than one board and place them side by side. In these boards it is necessary to use many cables to connect the components that are distant from each other. This is a very usual practice and it can almost be said that even if they geometrically form part of the network of contacts systems, in reality they are a cabled system. Just like in the cabled systems, the assemblies done over these boards are very difficult to follow and distinguish. Nonetheless, they do have some clear advantages, such as that the assemblies occupy very little space, or that integrated circuits can be connected directly.2.1.2.6. Hook-up network (Kopplungsraster): in the networks mentioned up to the moment, each group normally presented four contacts. However, in the hook-up network, each group makes use of only two contacts hence each group allows only the communication of two leads or pins of electronic components. If a ramification needs to be done, special parts need to be connected. The main disadvantage of this system is the cost and the large space necessary for its assembly. A famous example of this type is the Lectron system. In this system the contacts are not done in the panel, but rather take place in the adjacent sides of the parts where the electronic components are contained. The containers are cubical and the contacts take place in the adjacent sides of the cubes which aside from having a metallic side also have magnets so that contact can be easily done.2.1.3. Ideal Characteristics:
Each one of the previous systems has advantages and disadvantages. It seems difficult to find a system that fully complies with all the ideal requirements, which could be the following: That the circuit assembled over the panel be easy to distinguish visually. There are systems wherein once the circuit has been assembled, although it may function, is difficult to visually distinguish the path of the current and appreciate its topology. A quick, simple and intuitive delineation is fundamental in order to capture what the circuit wants to show. This is also very important for distinguishing errors and for comparing the assembly with the model that comes with the instructions.
That the Circuit be Easy to Assemble Following the Enclosed Circuit Diagram:
This point is related to the previous one. When the one that is assembling the circuit does not understand well its functioning, it has to follow the diagram which comes with the assembly instructions. The clearer the graphical representation of the assembly to be done, the easier will be its execution.
That Free Circuits be Easy to Assemble:
Free circuits should be easy to build. Free circuits are those devised by the user. If, in order to assemble one's own circuit, it is necessary to embark on a thorough prior planning, it is possible that such difficulty will hamper the creative and experimental inclinations of the beginner. This is very crucial when there is a need to make some corrections or modifications to the topology.
That Some Elements can be Easily Substituted with Another:
When one is learning electronics or experimenting with new circuits, it is essential that an element can be easily changed with another of different magnitude; this applies to resistors, condensers, inductances, etc.
That the Assemblies Occupy Little Space:
The more compact the assemblies, the less space they occupy, the more complex the circuits that can be assembled in a specific panel. For the same purpose, the less space the assemblies occupy, the lesser the size needed for the panel, and hence, the lesser the space to be occupied by the educational system, game or learning device.
That the Electronic Components be Well Identified:
It is important that the legends or labels of the different units or parts be easy to read. This is essential in order to choose the correct parts and also to understand well the circuit once it has been assembled.
2.1.4. Framework of the Proposed System
Taking into account the previous classification, the system being proposed would topologically be a network of contacts system. Specifically it is about a network of contact points, or a grid of contacts. The contact points are done through magnets with a conductive surface. These magnets are attached to a ferromagnetic panel in specific points of the grid. When the ferromagnetic contact plates of the building blocks coincide in the surface, this gives rise to an electric contact. In each contact point, four different contact plates can coincide, each one from a building block. The plates that meet at one contact point are separated 90° from each other. Similarly to what occurs in the Philips system already mentioned, the grid in this case does not count with a magnet in each point in a fixed way but rather magnets are placed where a contact needs to be done, according to the circuit referred to. In this manner the number of magnets that the system should consist of is reduced, making the product cheaper. The invention can also be considered as a network of crosses since even if the contacts are done in the magnetic surface, which is similar to a point, in general there is no direct plate-to-plate contact but rather the most usual manner of contact is plate-magnet-plate.
2.2. Most Related Documents
What we have done up to this point is to make a general description of the background art. Below follows a commentary of two documents that are considered most related to the proposed invention.
Systems that fix components to a metallic ferromagnetic base with the use of magnets are known in the art. Two documents which are considered most related to the present invention are the French document FR 2412128 A1 of the company Telemecanique Electrique, published on Jul. 13, 1979, and the document WO 98/25253 A1 of L. Black et al., published on Jun. 11, 1998.
2.2.1. Document FR 2412128 A1 offers a system with which to teach Electronics by assembling simple electric circuits. The system is designed for the use of large instruments, such as analogical ammeters and voltmeters, lamps, switches, etc. The components are attached to a ferromagnetic panel which is placed in a vertical or inclined position which can be shown to a class of students. The components are attached to the panel through ferrite magnets. Given that ferrite is not a conductive element, the magnets have a small copper covering on the surface which does not have any contact with the panel, that is, in the surface that the electric components touch. The components are attached to the magnets through ferromagnetic steel sheets which serve the purpose of mechanical fixation and also of electrical connection. When two or more steel sheets of two or more components coincide on the copper covering of the magnet, an electrical union occurs. There are also steel sheets which electrically connect magnets but do not form part of any component. That is, these steel sheets serve the purpose of an electric jumper.2.2.2. The document WO 98/25253 A1 shows a system to construct electrical and electronic circuits for educational purposes. The system is very similar to the one illustrated by the French document mentioned before: it comprises a ferromagnetic base plate on top of which some magnetic strips are fixed. These strips have a conductive layer on the upper side. This layer can be a coating or a metallic sheet. In a preferred embodiment the layer is a conducting adhesive strip of copper or tinned copper. Similar to the French document, the magnetic strips can be connected by conducting plates or by components. The permanent magnets have a mechanical function and at the same time an electrical function, since they electrically connect the different components that meet in them. The electrical or electronic components are mounted on an insulating base and are electrically connected to steel rivets that go through the insulating base. These steel rivets are the ones that make the contact with the conducting layer of the permanent magnets due to the attraction force that arises between them.
In a preferred embodiment, the leads of the components go through the insulating base across perforations that in the opposite side are surrounded by a copper pad connected to a copper track. These copper tracks connect each component lead with the copper pad of a rivet. The assembly is wave soldered. The rivets are fixed after soldering to make an electrical connection with the copper track.
Alternatively, the insulating base of each electronic component may be surfaced on its underside with strips of conductive material which are connected to the component.